Simultaneous analysis of butyltins and total tin in sediments as a tool for the assessment of tributyltin behaviour, long-term persistence and historical contamination in the coastal environment

Microbial communities as indicators of marine ecosystem health: Insights from coastal sediments in the eastern Adriatic Sea

Considering the adaptability and responsiveness of microorganisms to environmental changes, their indicator potential is still not acknowledged in European directives. This comprehensive study examined the changes of microbial communities in sediments and a range of geochemical parameters from pristine and anthropogenically impacted coastal areas in the eastern Adriatic Sea. Various analytical methods found evidence of sediment contamination (high toxicity level, enrichments of metals, tributyltin) in certain areas, leading to the categorization of sediments based on the level of anthropogenic disturbance. Prokaryotes were identified as the most promising group of microbes for further research, with specific bacterial families (Rhodobacteraceae, Ectothiorhodospiraceae, Cyclobacteriaceae) and genera (Boseongicola, B2M28, Subgroup 23, Sva0485, Thiogranum) proposed as potential indicators of environmental status. Finally, predictive models were developed to identify key indicator variables for assessing anthropogenic impact in sediments. This research represents an essential step toward incorporating microbial communities into assessments of benthic environmental health.

Update on the status of the contamination by organotin compounds in sediment of Nuevo Gulf, Argentina. Insights from field and experimental studies

Organotin compounds are persistent pollutants and are considered chemicals of high environmental concern. In the present study, the distribution and degradation of tributyltin were evaluated in field sediments and through an ex situ experiment. For this, sediment samples from two locations were analysed: Luis Piedrabuena Harbour, with higher maritime traffic, and Cerro Avanzado, which receives less impact from anthropogenic activities. The results indicated that pollution levels at Luis Piedrabuena Harbour have decreased compared with studies performed 9 years ago for the same area. On the contrary, traces of organotin compounds have been found for the first time at Cerro Avanzado. Moreover, the butyltin degradation index indicated that organotin compounds undergo an advanced degradation process in the collected samples at both sites. Ex situ experiments revealed a limited capacity of sediments to retain tributyltin, and suggested an active role of bioturbation activity in the degradation of these compounds. In addition, visualisation using chemometric techniques (principal components analysis) allowed a simpler analysis of two sediment characteristics: the degree of contamination and the degradation levels of organotin compounds.

Spatial distribution and temporal trends of butyltin compounds (TBT, DBT & MBT) in short sediment cores of the SW Portuguese Shelf (western Iberian Margin, NE Atlantic)

Spatial patterns and temporal trends of the butyltin compounds tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) were investigated in a set of sediment samples collected along the SW Portuguese continental shelf. This region did not reach the Good Environmental Status (GES) in accordance with the Marine Strategy Framework Directive (MSFD) during a first evaluation carried out in 2012. Overall, MBT and DBT were the predominant organotin species detected, but high concentrations of TBT were found in and around disposal sites for dredge sludge derived from the dredging in navigation channels, harbours, and shipyard facilities of the Tagus and Sado estuaries. Although Portuguese regulations for monitoring sediment quality in relation to dredging activities consider only PAH, PCB and HCB, they also dictate that other organic contaminants such as butyltin compounds (BTs) should be monitored if suspicion of high values exists, but no action limits are defined for these (MAOTDR, 2007). Without action limits, the monitoring recommendation given in the regulations is not put into practice. Considering their toxicity, BT derivates should be integrated in the legislation, because they represent an environmental threat in the relocation of dredged material, especially when derived from harbour and shipyards areas. Based on this study, we recommend giving more attention to the amounts and impacts of BTs in sediments at dredged material disposal sites (DMDS) and their surroundings. Or even better, in order to be more efficient, monitoring should be done at the source of the dredged materials and not at the sink. In case it is not done, the monitoring of concentrations of TBT (and other BTs) in sediments and organisms, including imposex studies, at all Portuguese sites for disposal of dredged material receiving slightly to strongly contaminated dredged material must be developed.

Current Status of Antifouling Biocides Contamination in the Seto Inland Sea, Japan

A monitoring survey of antifouling biocides was conducted in the Harima Nada Sea and Osaka Bay of the Seto Inland Sea, Japan to assess contamination by organotin (OT) compounds and alternative biocides. The concentrations of tributyltin (TBT) compounds in surface water ranged from 1.0 to 2.8 ng/L, and the detected TBT concentrations in the bottom water layer were higher than those in the surface water. The concentrations of TBT compounds in sediment samples ranged from 2.0 to 28 ng/g dry weight (dw), respectively. The concentrations of alternative biocides in the water and sediment were lower than those before the banning of TBT by the International Maritime Organization (IMO). Although triphenyltin (TPT) compounds were not detected in water samples, TPT compounds were detected in the range of < 0.1-2700 ng/g dw in sediment samples. Their concentrations in the water samples were as follows: diuron, < 1-53 ng/L; Sea-Nine 211, < 1-1.8 ng/L; Irgarol 1051, < 1-4.0 ng/L; dichlofluanid, < 1-343 ng/L; and chlorothalonil, < 1-1 ng/L, and the ranges of these alternative compounds in sediment samples were diuron, 32-488 ng/g dw; Sea-Nine 211, 47-591 ng/g dw; Irgarol, 33-128 ng/g dw; dichlofluanid, 67-8038 ng/g dw; and chlorothalonil, 31-2975 ng/g dw. Thus, the OTs and alternative biocides have still been detected in water and sediment samples from closed sea areas.

Tributyltin degrading microbial enzymes: A promising remediation approach

Brazil is one of the countries most impacted along the entire coastline by the presence of tributyltin (TBT), a biocide used in antifouling paints. Despite being banned since 2008, its use is still registered in the country, and it is possible to find recent inputs of this substance in places under the influence of shipyards, marinas, and fishing ports. In this study, a bacterium isolated from TBT-contaminated sediment from Santos and São Vicente Estuarine System (SESS) in Brazil, identified as Achromobacter sp., proved to be resistant to this compound. Furthermore, its crude enzymatic extract presented the ability to reduce up to 25 % of the initial TBT concentration in the liquid phase in 1 h, demonstrating to be a simple, fast, effective procedure and a potential tool for the environmental attenuation of TBT.

The study on contamination of bottom sediments from the Odra River estuary (SW Baltic Sea) by tributyltin using environmetric methods

We present the first comprehensive study on the occurrence of tributyltin (TBT) in the Odra River estuary (SW Baltic Sea) that encompasses both densely populated and urbanized agglomeration Szczecin city, and sparsely populated biosphere reserves "Natura 2000". Relationship between TBT and physicochemical parameters of bottom sediments such as granulometry total organic carbon (TOC), total nitrogen (TN), acid volatile sulfide (AVS), As, and metals: Ba, Cd, Co, Cr, Cu, Fe, Hg, Ni, Mn, Mo, Pb, Sn, and Zn was investigated in 120 samples collected in 2017 and 2018. The highest TBT concentrations were over 3000 ng g^-1 (dry weight). They were observed in samples collected in the vicinity of the ship maintenance zones of the Szczecin city. Despite the EU ban on its use since 2003, TBT is still present in the environment. Environmetrics analyses such as correlation, cluster, and principal component analysis of obtained results revealed that the main source of sediments contamination by TBT, metalloids, and metals is likely related to the maritime industry: shipyards, ship maintenance as well as ports and marines. TBT is still present in the bottom sediments because of its emission to the environment with dust and paint chips formed during sandblasting cleaning of ship surfaces. The pollutant is further transported with water current to remote localization in the Szczecin Lagoon. Slow water exchange between the Szczecin Lagoon and the Baltic Sea favors accumulation of pollutants in the lagoon sediments. Therefore, it is necessary to implement environmentally friendly methods into ship maintenance and management of the materials from dredged waterways, harbors, and marinas.

First assessment of butyltins (BuTs) contamination of the Montenegrin coast (Southeast Adriatic): Tributyltin (TBT) poses a threat to the marine ecosystem

This study presents the first assessment of butyltins (BuTs) pollution of the Montenegrin coast. The distribution of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) was investigated in mussels, sediments and water overlying sediment after the sediment resuspension. The results showed that the investigated sites (marinas, ports, shipyards) are contaminated with BuTs (19-402 ng (Sn)/g in mussels; 43-20,641 ng (Sn)/g in sediments; 9-566 ng (Sn)/L in overlying waters). The measured TBT concentrations indicate that toxic effects on marine organisms are expected at most locations. The simultaneous analysis of BuTs and total Sn in sediment cores allowed the assessment of TBT historical input, while it was demonstrated that resuspension of contaminated sediments leads to the release of all BuTs into the water column. This study shows that, despite the ban of TBT-based antifouling paints more than a decade ago, pollution of the marine environment with TBT is still a problem and regular monitoring remains essential.

Toxicity of tributyltin chloride on haarder (Liza haematocheila) after its acute exposure: Bioaccumulation, antioxidant defense, histological, and transcriptional analyses

Liza haematocheila is exposed to various chemical contaminants from anthropogenic sources, including tributyltin chloride (TBTC). Yet the toxicity mechanism of TBTC on haarder remains unclear. The haarder was exposed to different doses (0, 10%, 20%, and 50% of LC₅₀-96 h) of TBTC. In this study, the results revealed its high bioaccumulation in the livers and significant alteration for development. The activities of antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase decreased after 96-h exposure to TBTC, this accompanied by an increased malondialdehyde level. TBTC exposure caused the intense production of reactive oxygen species, a reduction in total blood cell count in serum, and apoptosis-related alterations in livers, indicating that enhanced oxidative stress occurred in the process of TBTC exposure. Histological results revealed angiorrhexis and infiltration of inflammatory cells, vacuolar degeneration of hepatocytes in the livers, and swelling, fusion, and disintegration of gill organs. Interestingly, the obtained transcriptional profiles indicated that high doses of TBTC caused energy disorder, apoptosis, and adipogenesis restriction mediated by cytokines and adipokines in Jak-STAT and adipocytokine signaling pathways. In summary, acute exposure to high doses of TBTC could impair the antioxidant system and pathways related to energy, apoptosis and adipogenesis, eventually posing a serious challenge to the fitness of haarder individuals and its fish populations as marine resources.

Origin and history of trace elements accumulation in recent Mediterranean sediments under heavy human impact. A case study of the Boka Kotorska Bay (Southeast Adriatic Sea)

The history of metal pollution in the semi-enclosed and human-influenced marine system of the Boka Kotorska Bay (Southern Adriatic) was studied considering geological composition of the surrounding catchment, the sedimentation rate and the mineralogical and early diagenetic processes in the recent sediments. The determination of background concentrations of metals, undertaken for the first time in this environment, proved to be particularly important for Ni and Cr, which are naturally enriched in the sediments of the southern Adriatic. The results showed widespread moderate contamination with Pb and Sn since the 1970s, while the upper layers of sediments near shipyards, marinas and urban areas were more contaminated with Sn, Cu, Pb, Zn, Cd, As, Sb and Mo. The transport of material through the narrow straits separating different parts of Boka Kotorska Bay resulted in a different geochemical composition of the smaller bays and a limited distribution of contaminated sediments from local sources.

Insights into the Restoration of Tributyltin Contaminated Environments Using Marine Bacteria from Portuguese Fishing Ports

Tributyltin (TBT) is an organotin chemical mainly used as biocide in marine antifouling paints. Despite the restrictions and prohibitions on its use, TBT is still an environmental problem due to its extensive application and subsequent release into the environment, being regarded as one of the most toxic chemicals released into the marine ecosystems. Microorganisms inhabiting impacted sites are crucial for their restoration since they have developed mechanisms to tolerate and break down pollutants. Nonetheless, transformation products resulting from the degradation process may still be toxic or, sometimes, even more toxic than the parent compound. The determination of the parent and degradation products by analytical methods, although necessary, may not be ecologically relevant since no information is provided regarding their ecotoxicity. In this study, marine bacteria collected from seven Portuguese fishing ports were isolated and grown in the presence of TBT. Bacteria that exhibited higher growth were used to bioremediate TBT-contaminated waters. The potential of these bacteria as bioremediation agents was evaluated through ecotoxicological assays using the sea snail Gibbula umbilicalis as model organism. Data suggested that some TBT-tolerant bacteria, such as Pseudomonas putida, can reduce the toxicity of TBT contaminated environments. This work contributes to the knowledge of TBT-degrading bacteria.